From: David Mosberger <davidm@napali.hpl.hp.com>
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Message-ID: <16877.60406.192245.106565@napali.hpl.hp.com>
Date: Tue, 18 Jan 2005 21:11:18 -0800
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Linus Torvalds <torvalds@osdl.org>, "Luck, Tony" <tony.luck@intel.com>,
       linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: pipe performance regression on ia64
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>>>>> On Wed, 19 Jan 2005 10:34:30 +1100, Nick Piggin <nickpiggin@yahoo.com.au> said:

  Nick> David I remember you reporting a pipe bandwidth regression,
  Nick> and I had a patch for it, but that hurt other workloads, so I
  Nick> don't think we ever really got anywhere. I've recently begun
  Nick> having another look at the multiprocessor balancer, so
  Nick> hopefully I can get a bit further with it this time.

While it may be worthwhile to improve the scheduler, it's clear that
there isn't going to be a trivial "fix" for this issue, especially
since it's not even clear that anything is really broken.  Independent
of the scheduler work, it would be very useful to have a pipe
benchmark which at least made the dependencies on the scheduler
obvious.  So I think improving the scheduler and improving the LMbench
pipe benchmark are entirely complementary.

	--david

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